The present invention relates to cooking apparatus, and more particularly relates to a unique convection steam apparatus and method for processing food items or the like with improved convection heat-transfer characteristics for more rapid and effective heating and/or cooking with high quality food characteristics, such as color, texture, flavor and taste. The apparatus and method of convection may be utilized for processing any raw and/or pre-cooked food items. The convection steamer and method of the present invention is particularly useful in commercial applications, such as restaurants, cafeterias, or the like, where quality and relatively rapid processing of considerable amounts of food items is desirable.
Heretofore, various types of steam cookers have been employed to increase the speed of cooking while attempting to retain the important criteria of food quality usually impaired by either under or over cooking. Steam cooking has been recognized as an effective process compared to dry heat cooking for the reason that, when steam contacts any surface temperature lower than itself, the steam condenses and transfers a comparatively vast amount of heat to the cooler surface (970 B.T.U./pound of steam). Moreover, prior cooking methods have not effectively overcome traditional barriers for optimum heat transfer. One such barrier is air; condensate is another. For example, the presence of only one half of one percent of air in the steam environment can reduce the heat transfer coefficient by as much as 50% for the reason that air acts as an insulative barrier around the food. Further, a cooking chamber containing an air/steam mixture can only supply the temperature of the partial pressure of the steam and not the total chamber pressure since the heat transfer coefficient of the pressurized air/steam environment is considerably less efficient than an atmospheric pure steam environment. Similarly, condensate forms on the food and insulates it against efficient heat transfer. In general, prior cooking methods have not utilized the maximum potential cooking energy of steam which is maintained at atmospheric pressure and at its lowest effective cooking temperature. Typical of prior art apparatus and methods are disclosed in the following patents; U.S. Pat. Nos. 3,071,063; 3,742,931; 3,071,473; 3,769,958; 3,503,322; 3,820,524.